after investigating block & removing it, continued with informal test and found a 2nd failure @ 85cm down on 25th tap. Slab of 1F RG 0.5mm that propagated (SP) on thin layer of F hard FC 2mm lying on a 1F hard MFcr.

bottom 1/3rd of pack consisted of well bonded facets that have rounded and at the ground are very moist & stuck to the grass. So we got that going for us, which is nice.

no other signs of instability on a short low angled tour, spooky stable underfoot.